The first object of the invention is a method of obtaining a carbide-graphene surface composite with a controlled surface morphology, especially a SiC-graphene composite, characterized in that the SiC substrate, especially with a crystalline or polycrystalline structure, after initial preparation is successively subjected to annealing and then cooling. The second object of the invention is a carbide-graphene composite on a SiC surface, with a crystalline or polycrystalline structure, obtained by the method as defined in the first object of the invention, containing from one to four atomic layers of graphene forming a honeycomb lattice, wherein their diffraction spectrum obtained by the low energy electron diffraction method has a diffraction pattern typical of graphene on the SiC surface, characterized by the fact that it contains a surface covered with terraces or a network of pits, the difference in height of the terraces is from 0.25×10.sup.−9 m to 2.5×10.sup.−9 m or the surface density of pits is at least 5×10.sup.12/m.sup.2.

The first object of the invention is a method of obtaining a carbide-graphene surface composite with a controlled surface morphology, especially a SiC-graphene composite, characterized in that the SiC substrate, especially with a crystalline or polycrystalline structure, after initial preparation is successively subjected to annealing and then cooling. The second object of the invention is a carbide-graphene composite on a SiC surface, with a crystalline or polycrystalline structure, obtained by the method as defined in the first object of the invention, containing from one to four atomic layers of graphene forming a honeycomb lattice, wherein their diffraction spectrum obtained by the low energy electron diffraction method has a diffraction pattern typical of graphene on the SiC surface, characterized by the fact that it contains a surface covered with terraces or a network of pits, the difference in height of the terraces is from 0.25×10.sup.−9 m to 2.5×10.sup.−9 m or the surface density of pits is at least 5×10.sup.12/m.sup.2.

The present invention relates to an SiC material and an SiC composite material and, more particularly, to an SiC material and an SiC composite material having a diffraction intensity ratio (I) of an X-ray diffraction peak, calculated by formula 1 down below, of less than 1.5. The present invention can provide an SiC material and an SiC composite material which can be etched evenly when exposed to plasma and thereby reduce the occurrence of cracks, holes and so forth. [Formula 1] Diffraction intensity ratio (I)=(peak intensity of plane (200)+peak intensity of plane (220))/peak intensity of plane (111).

The present invention relates to an SiC material and an SiC composite material and, more particularly, to an SiC material and an SiC composite material having a diffraction intensity ratio (I) of an X-ray diffraction peak, calculated by formula 1 down below, of less than 1.5. The present invention can provide an SiC material and an SiC composite material which can be etched evenly when exposed to plasma and thereby reduce the occurrence of cracks, holes and so forth. [Formula 1] Diffraction intensity ratio (I)=(peak intensity of plane (200)+peak intensity of plane (220))/peak intensity of plane (111).

A silicon carbide single crystal wafer and a preparation method therefor, a silicon carbide crystal and a preparation method therefor, and a semiconductor device. The surface of the silicon carbide single crystal wafer is such that an included angle between a normal direction and a c direction is 0-8 degrees, and aggregated dislocations on the silicon carbide single crystal wafer are less than 300/cm.sup.2; the aggregated dislocation is a dislocation aggregated condition in which the distance between the geometric centers of any two corrosion pits in the corrosion pits obtained after corrosion of melted KOH is less than 80 microns. Even if the dislocation density is relatively high, the aggregated dislocation density is relatively small, thereby increasing the yield of a silicon carbide-based devices.

A silicon carbide single crystal wafer and a preparation method therefor, a silicon carbide crystal and a preparation method therefor, and a semiconductor device. The surface of the silicon carbide single crystal wafer is such that an included angle between a normal direction and a c direction is 0-8 degrees, and aggregated dislocations on the silicon carbide single crystal wafer are less than 300/cm.sup.2; the aggregated dislocation is a dislocation aggregated condition in which the distance between the geometric centers of any two corrosion pits in the corrosion pits obtained after corrosion of melted KOH is less than 80 microns. Even if the dislocation density is relatively high, the aggregated dislocation density is relatively small, thereby increasing the yield of a silicon carbide-based devices.

A negative electrode active material including a silicon-carbon-based particle, the silicon-carbon-based particle having a SiC.sub.x matrix and boron doped in the SiC.sub.x matrix, wherein x of the SiC.sub.x matrix is 0.3 or more and less than 0.6.

A SiC powder containing 70% by mass or more of a β-SiC, wherein in a volume-based cumulative particle size distribution measured by a laser diffraction method, a D50 is 8 to 35 μm and a D10 is 5 μm or more.

A SiC powder containing 70% by mass or more of a β-SiC, wherein in a volume-based cumulative particle size distribution measured by a laser diffraction method, a D50 is 8 to 35 μm and a D10 is 5 μm or more.

Organosilicon chemistry, polymer derived ceramic materials, and methods. Such materials and methods for making polysilocarb (SiOC) and Silicon Carbide (SiC) materials having 3-nines, 4-nines, 6-nines and greater purity. Processes and articles utilizing such high purity SiOC and SiC.